METplus Practical Session Guide (Version 5.0) | MET Tool: Gen-Vx-Mask > Run Poly Type

Start by making an output directory for Gen-Vx-Mask and changing directories:

Since Gen-Vx-Mask performs a simple masking step, no configuration file is needed.

We'll run the Gen-Vx-Mask tool to apply a polyline for the CONUS (Contiguous United States) to our model domain. Run Gen-Vx-Mask on the command line using the following command:

Re-run using verbosity level 3 and look closely at the log messages. How many grid points were included in this mask?

Gen-Vx-Mask should run very quickly since the grid is coarse (185x129 points) and there are 243 lat/lon points in the CONUS polyline. The more you increase the grid resolution and number of polyline points, the longer it will take to run. View the NetCDF bitmap file generated by executing the following command:

Notice that the bitmap has a value of 1 inside the CONUS polyline and 0 everywhere else. We'll use the CONUS mask we just defined in the next step.

You could try running plot_data_plane to create a PostScript image of this masking region. Can you remember how?

Notice that there are several ways that gen_vx_mask can be run to define regions of interest, some of which will be demonstrated over the next few pages.